/* This function generates a sequence of nodes by a depth-first traverse in
 * pre-order, this is for verifying if the BST is well balanced. */
int traverseBBSTPreOrder(BBST tree, DQueue lines, int maxcount)
{
	BBSTNode 	p 		= tree->Root;
	DQueueData 	stack;

	initializeDQueue(&stack, tree->Context);

	while( stack.NodeCount > 0 || p != NULL ) {
		if ( p != NULL ) {
			insertDQueueTailNode(lines, p);
			insertDQueueHeadNode(&stack, p);
			p = p->Left;

			if ( maxcount > 0 && getDQueueLength(lines) == maxcount ) {
				break;
			}
		}
		else {
				p = (BBSTNode)removeDQueueHeadNode(&stack);
				p = p->Right;
		}
	}

    removeAllDQueueNodes(&stack);
	cleanDQueue(&stack);

	return FUNC_RETURN_OK;
}
/******************************************************************************
 * I aM Alive.
 *
 * Request:
 *         |<----------- 64 bits (8 bytes) ----------->|
 *         +----------+--------------------------------+
 *         |  TDC     |  BDC     |     Reserved        |
 * 		   +----------+----------+---------------------+
 *         |                                           |
 *         |             Machine ID info               |
 *         |                                           |
 * 		   +-------------------------------------------+     _____ 64bit aligned
 *
 * Response:
 *         |<----------- 64 bits (8 bytes) ----------->|
 *         +---------------------+---------------------+
 *         |  heartbeat result   |    Reserved   	   |
 * 		   +---------------------+---------------------+     _____ 64bit aligned
 *
 ******************************************************************************/
int sendIMAlive(int  *errorcode,
				char *errorbuf,
				int	  errorbufsize)
{
	int 				res 					= FUNC_RETURN_OK;
	AsyncCommBuffer		newcommbuffer			= NULL;

	Assert( DRMGlobalInstance->LocalHostStat != NULL );

	/* Build request. */
	SelfMaintainBufferData tosend;
	initializeSelfMaintainBuffer(&tosend, PCONTEXT);

	RPCRequestHeadIMAliveData requesthead;
	requesthead.TmpDirCount 	  = getDQueueLength(&DRMGlobalInstance->LocalHostTempDirectories);
	requesthead.TmpDirBrokenCount = DRMGlobalInstance->LocalHostStat->FailedTmpDirNum;
	requesthead.Reserved		  = 0;

	appendSMBVar(&tosend, requesthead);
	appendSelfMaintainBuffer(&tosend,
							 (char *)(DRMGlobalInstance->LocalHostStat),
							 offsetof(SegStatData, Info) +
							 DRMGlobalInstance->LocalHostStat->Info.Size);

	/* Set content to send and add to AsyncComm framework. */
	AsyncCommMessageHandlerContext context =
			rm_palloc0(AsyncCommContext,
					   sizeof(AsyncCommMessageHandlerContextData));
	context->inMessage				 = false;
	context->UserData  				 = NULL;
	context->MessageRecvReadyHandler = NULL;
	context->MessageRecvedHandler 	 = receivedIMAliveResponse;
	context->MessageSendReadyHandler = NULL;
	context->MessageSentHandler		 = sentIMAlive;
	context->MessageErrorHandler 	 = sentIMAliveError;
	context->MessageCleanUpHandler	 = sentIMAliveCleanUp;

	/* Connect to HAWQ RM server */

	res = registerAsyncConnectionFileDesc(NULL,
										  DRMGlobalInstance->SendToStandby?
										  standby_addr_host:
										  master_addr_host,
										  rm_master_port,
										  ASYNCCOMM_READBYTES | ASYNCCOMM_WRITEBYTES,
										  &AsyncCommBufferHandlersMessage,
										  context,
										  &newcommbuffer);
	if ( res != FUNC_RETURN_OK )
	{
		rm_pfree(AsyncCommContext, context);
		elog(WARNING, "Fail to register asynchronous connection for sending "
					  "IMAlive message. %d", res);
		return res;
	}

	buildMessageToCommBuffer(newcommbuffer,
							 tosend.Buffer,
							 tosend.Cursor + 1,
							 REQUEST_RM_IMALIVE,
							 0,
							 0);

	destroySelfMaintainBuffer(&tosend);

	context->AsyncBuffer = newcommbuffer;

	InitHandler_Message(newcommbuffer);

	return FUNC_RETURN_OK;
}